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Explore  /  MGF / PEG-MGF (Mechano Growth Factor, IGF-1Ec)

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MGF / PEG-MGF (Mechano Growth Factor, IGF-1Ec)

D

lead outcome

Satellite-cell (muscle stem-cell) activation…

grades vary by outcome ↓

Peptide⚠ WADA-banned

also called — MGF · Mechano Growth Factor · IGF-1Ec (human; IGF-1Eb in rodents) · the IGF-1 E-peptide (Ec) · PEG-MGF / PEGylated MGF (the long-acting form). INCI: none

muscle growth / repairsatellite-cell (stem-cell) activationtissue repair(IGF-1 axis, early proliferative phase)

The "first responder" of muscle repair — elegant splice-variant biology, almost entirely preclinical. Three points define this entry: (1) it's a genuinely distinct piece of biology — an IGF-1 splice variant whose unique E-peptide activates muscle stem (satellite) cells, a different job from ordinary IGF-1; (2) native MGF has a ~5-7 minute half-life by design, so the gray market sells PEG-MGF (PEGylated) to extend it — introducing its own quality-control problem; (3) despite rich mechanism, human data are very limited and the "artificially switching on muscle stem cells" question has no long-term safety data.

In brief

MGF (Mechano Growth Factor, IGF-1Ec) is a splice variant of IGF-1 produced locally in muscle in response to mechanical stress or damage. Its distinctive part is a 24-amino-acid E-peptide that acts as an early "first responder" repair signal — it wakes up quiescent satellite cells (muscle stem cells) and makes them proliferate, a job the ordinary circulating IGF-1 doesn't do well. In the natural repair cascade, this MGF pulse comes first (within hours), expanding the stem-cell pool, and is followed by a switch to IGF-1Ea, which drives the actual fiber growth. The biology is elegant and real — but it's overwhelmingly preclinical. Native MGF has an extremely short half-life (~5-7 minutes) by design (it's meant to be a local, transient signal), which is why the gray market sells PEG-MGF (PEGylated, longer-acting) — a form that carries batch-to-batch inconsistency and still lacks meaningful human trials. Add no long-term safety data on artificially activating muscle stem cells, and the honest read is: interesting mechanism, minimal human proof.

Legal standing, by region

European Union

Not FDA-approved (gray-market)

not approved anywhere; investigational research peptide. Not a cosmetic; no compounding pathway.

⚠ WADA-prohibited in sportSport as an IGF-1/growth-factor agent, it falls in WADA-prohibited growth-factor territory.

Evidence, by outcome

How we grade →

An honest grade per outcome — drawn from the evidence, not any catalogue. Hype and undemonstrated marketing claims grade low.

OutcomeEvidence base · effectGrade

Satellite-cell (muscle stem-cell) activation / proliferation

Genuinely distinct, reproducible preclinical biology — but not demonstrated as a human therapy

Well-characterised in cell/animal models — MGF E-peptide activates quiescent satellite cells where mature IGF-1 barely does

D

Muscle repair / hypertrophy (the marketed use)

Very limited human data; no controlled human hypertrophy/repair trials establishing efficacy

Animal / model data on the MGF→IGF-1Ea repair cascade

F

Aged-muscle / regeneration

Interesting rationale (maybe why older muscle repairs slower) — but human interventional data absent

Observation: aged muscle shows a blunted MGF response to loading vs young

F

PEG-MGF as a practical agent

Solves the half-life problem mechanically, but subcutaneous kinetics not formally characterised, and unregulated PEG products vary widely batch-to-batch

PK: PEGylation extends half-life from ~minutes to ~hours/≈24 h

—

Safety

Injection-site pain/swelling common; no long-term data on chronically/artificially activating muscle stem cells; theoretical concerns (scar tissue, unregulated growth signalling) unquantified

Little formal human data

—

Disclosure

Vallydia sells its own cosmetic serums, and some ingredients graded here belong to the same categories as those products. Grades are drawn from the published evidence by the method we publish, and applied to our own ingredients on the same terms — our copper-peptide serum is graded no more kindly than the peptides it competes with. We disclose the interest so you can weigh it.

Trade names shown here (for example Matrixyl, Argireline, Syn-Ake) are the property of their respective owners and are used only to identify the ingredient under discussion. Their appearance implies no affiliation with, or endorsement by, the proprietor.

Evidence changes

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Identity

MGF is a splice variant of the IGF-1 gene (chromosome 12q23). The IGF-1 gene splices exons 4-6 into several isoforms that share the same mature IGF-1 sequence but differ in a C-terminal "E-peptide." MGF's distinguishing feature is its unique 24-amino-acid E-peptide (from a reading-frame shift in exon 5), which has biological activity of its own, independent of the mature IGF-1 domain. The synthetic "MGF" sold for research is typically just this E-peptide. PEG-MGF attaches polyethylene-glycol chains to it to extend its very short half-life.

Mechanism (as proposed)

the IGF-1 gene produces multiple isoforms by alternative splicing. Two matter for muscle: IGF-1Ea (the liver-derived, circulating, systemic anabolic form — "tonic" growth signal) and IGF-1Ec = MGF (the local, mechano-responsive form). When muscle is loaded or damaged, it transiently makes MGF within hours; MGF's E-peptide then activates satellite cells (muscle stem cells sitting dormant between fibers), driving them to proliferate — critically, without forcing early differentiation, so the stem-cell pool expands first. The muscle then switches to IGF-1Ea, whose mature IGF-1 acts via IGF-1R → PI3K/Akt/mTOR to drive myoblast fusion, protein synthesis and fiber hypertrophy. So MGF is the early proliferative trigger; classic IGF-1 is the later growth executor. MGF biology is therefore not simply "more IGF-1" — the E-peptide works through partly different pathways to achieve a different early outcome (proliferation vs differentiation).

Chemical identifiers

Cross-reference identifiers for the authoritative external databases — not a recipe, and nothing about how to use it.

PubChem CID447728

InChIKeyGJOMWUHGUQLOAC-UHFFFAOYSA-K

SMILES[F-].[F-].[F-].[Mg+2]

via PubChem exact-name match (MGF) · high confidence

Sources — 5 cited

01Goldspink G, et al. — characterization of MGF/IGF-1Ec as the mechano-responsive IGF-1 splice variant (UCL, mid-1990s onward); E-peptide autonomous activity.

02Reviews of IGF-1 splice isoforms and the MGF→IGF-1Ea repair cascade / satellite-cell activation (Hill & Goldspink and successors).

03PEGylation pharmacology for MGF (half-life extension; note un-formalised SC kinetics and batch variability in unregulated products).

04Observations of blunted MGF response in aged skeletal muscle after loading/injury.

05(Note: as of 2026, human interventional efficacy/safety data for exogenous MGF/PEG-MGF remain very limited.)

Updated 2026-07-13 (watch for any controlled human data — the field is preclinical-heavy; that would move the grades)

Grades reflect the published evidence, not our interest. No dosing, reconstitution, or administration is published for research compounds — that restraint is deliberate.

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